JP2023137055A - Surface protection film and film laminate - Google Patents

Abstract

To provide a surface protection film with a functional layer that has antibacterial properties equivalent to silver antibacterial agents, and yet remains free of discoloration and excels in resistance to UV and halogens, and to provide a film laminate.SOLUTION: A surface protection film includes (A) a functional layer including ammonium salt-modified nanocellulose, a substrate layer and an adhesive layer, which are laminated in the stated order.SELECTED DRAWING: None

Description

The present invention relates to a surface protection film and a film laminate.

In recent years, from the perspective of a circular economy (sustainable society), high-performance materials using plant-derived materials have been attracting attention. Suggestions have been made.

Chemically modified nanocellulose materials, which are made by chemically modifying the surface of cellulose nanomaterials, are being considered for use in a variety of applications because of their excellent transparency and functionality.
For example, Patent Document 1 discloses a technique in which a coating liquid containing cellulose nanofibers and inorganic particles is applied onto a base film to improve mechanical strength.
Further, Patent Document 2 discloses a functional material using chemically bonded silica xerogel or silica airgel and cellulose nanofiber as a heat insulating material.
Furthermore, in Non-Patent Document 1, a study has been made in which cellulose nanofiber airgel prepared by freeze-drying is subjected to silylation treatment by dipping and applied as an oil-water separation membrane.
In recent years, due to the spread of COVID-19, techniques for imparting antibacterial properties to the surfaces of various products and members have been attracting attention, and various antibacterial agents have been proposed. They are broadly classified into inorganic antibacterial agents and organic antibacterial agents, but silver-based antibacterial agents, which are inorganic antibacterial agents, are particularly safe, durable, heat resistant, etc., and can be used in a wide variety of applications. has been done.

Japanese Patent Application Publication No. 2010-155427 JP2014-237910A Japanese Patent Application Publication No. 2015-189196

S. Zhou et al., ACS Sustainable Chem. Eng. 2016, 4, 6409-6416

However, silver-based antibacterial agents that are currently widely used have poor UV resistance, and when placed in a sunlight environment for a long period of time, the silver, which is an antibacterial component, is oxidized and discolored.
Therefore, efforts have been made to improve light resistance (for example, Patent Document 3), but this has not always been sufficient. Furthermore, in applications in the medical field, wiping disinfection using sodium hypochlorite, a chlorine-based disinfectant, is recommended to prevent secondary infections, but when using silver-based antibacterial agents, There were problems with poor halogen resistance and discoloration due to oxidation of silver.

Therefore, an object of the present invention is to obtain a surface protection film that does not discolor, has antibacterial properties comparable to silver-based antibacterial agents, and has a functional layer with good UV resistance and halogen resistance.

In view of the above-mentioned circumstances, the present inventors have conducted extensive studies and found that the above-mentioned problems can be easily solved by providing a functional layer containing nanocellulose with a specific composition, and have completed the present invention. Ta. That is, the present invention provides the following [1] to [19].

[1] (A) A surface protection film in which a functional layer containing ammonium salt-modified nanocellulose, a base layer, and an adhesive layer are sequentially laminated.
[2] The surface protection film according to [1] above, wherein (A) ammonium salt-modified nanocellulose is (A') quaternary ammonium salt-modified nanocellulose.
[3] The surface protection film according to [1] or [2] above, wherein the functional layer further contains (B) a binder resin.
[4] The surface protection film according to [3] above, wherein (B) the binder resin is a water-soluble polymer.
[5] The surface protection film according to [4] above, wherein the water-soluble polymer is a polyvinyl alcohol resin or an acrylic resin.
[6] The surface protection film according to any one of [1] to [5] above, further comprising a primer layer between the functional layer and the base layer.
[7] The surface protection film according to [6] above, wherein the primer layer contains a polyvalent cation resin.
[8] The surface protection film according to [7] above, wherein the polyvalent cation resin is polyethyleneimine.
[9] The surface protection film according to any one of [1] to [8] above, wherein the functional layer has a thickness (after drying) of 10 nm or more and 1,000 nm or less.
[10] The surface protection film according to any one of [1] to [9] above, wherein the base material layer is a resin film, a fibrous base material, or glass.
[11] The surface protection film according to [10] above, wherein the resin film is a polyester film.
[12] The surface protection film according to any one of [1] to [10] above, wherein the adhesive layer is silicone-based, acrylic-based, or urethane-based.
[13] The surface according to any one of [1] to [12] above, which has an antibacterial activity value of 3 or more against Staphylococcus aureus after being irradiated with ultraviolet light of 340 to 400 nm at 60 W/m ² for 10 hours. Protective film.
[14] The surface protection film according to any one of [1] to [13] above, which has an antibacterial activity value of 3 or more for E. coli after irradiation with ultraviolet rays of 340 to 400 nm at 60 W/m ² for 10 hours. .
[15] A film laminate in which the surface protection film according to any one of [1] to [14] above is laminated to an adherend.
[16] The film laminate according to [15] above, wherein the adherend is a release film.
[17] The film laminate according to [15] above, wherein the adherend is glass.
[18] The surface protection film according to any one of [1] to [14] above, which is for a smart mirror.
[19] The film laminate according to [15] or [17] above, wherein the adherend is a smart mirror.

The surface protection film of the present invention is environmentally friendly, has antibacterial properties comparable to silver-based antibacterial agents, does not discolor, and has a functional layer with good UV resistance and halogen resistance. I can do it. More specifically, the surface of the functional layer has a characteristic that the antibacterial activity value (Staphylococcus aureus) after UV irradiation is 3 or more, or the antibacterial activity value (Escherichia coli) after UV irradiation is 3 or more. In addition, the functional layer-coated base material constituting the surface protection film of the present invention can be produced by applying the functional layer to the base material, heating it, and treating it with active energy rays, so continuous production is possible and productivity is high. expensive. Furthermore, since the surface protection film of the present invention has good antibacterial properties, it can be used as a protective film that is used by touching the surface of an adherend multiple times with a fingertip, whether indoors or outdoors, such as a smart mirror. Suitable for this purpose.

Next, an example of an embodiment of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and can be implemented with various modifications within the scope of the gist.

<Surface protection film>
A surface protection film according to an embodiment of the present invention (hereinafter also referred to as "this surface protection film") has a functional layer containing ammonium salt-modified nanocellulose, a base material layer, and an adhesive layer laminated in this order. .

In the present invention, "nanocellulose" refers to cellulose that has been crushed to the nano level by mechanical or chemical treatment. Containing "nanocellulose" can be determined by observation with an electron microscope, IR spectroscopy, etc.
"Ammonium salt-modified nanocellulose" means a reaction product of nanocellulose and an ammonium salt-containing compound. Preferably, an ammonium salt structure is introduced into the 6-position hydroxyl group of the β-glucose group constituting cellulose. Whether the surface protection film contains "ammonium salt-modified nanocellulose" can be determined by XPS elemental analysis or the like.

From the viewpoint of ease of handling, the total thickness of the surface protection film is preferably 250 μm or less, more preferably 25 μm or more and 200 μm or less, still more preferably 38 μm or more and 125 μm or less, and still more preferably 38 μm or more and 100 μm or less. The total thickness of the surface protection film is the total thickness of the functional layer, base material layer, and adhesive layer.

Each layer constituting the present surface protection film will be explained below.

1. Functional Layer The functional layer of the present surface protection film constitutes one surface of the present surface protection film and must contain ammonium salt-modified nanocellulose.
At this time, the content of ammonium salt-modified nanocellulose in the functional layer can be adjusted at any ratio. For example, it is preferably 10% by mass or more and 90% by mass or less, especially 10% by mass or more and 80% by mass or less of the material constituting the functional layer.
Note that this functional layer may contain unmodified nanocellulose. In that case, it is preferable that the amount of ammonium salt-modified nanocellulose is greater than the amount of unmodified nanocellulose.

[(A) Ammonium salt modified nanocellulose]
The ammonium salt-modified nanocellulose contained in this functional layer is a reaction product of unmodified nanocellulose and an ammonium salt-containing compound.

The ammonium salt structure of the ammonium salt-modified nanocellulose is preferably represented by the following general formula (1) or general formula (2).

In the formula, R ¹ and R ² are each independently a hydrogen atom or a linear or branched aliphatic hydrocarbon group having 1 to 22 carbon atoms (such as an alkyl group and an alkenyl group), and R ³ is a hydrogen atom or a linear or branched aliphatic hydrocarbon group having 1 to 22 carbon atoms (such as an alkyl group and an alkenyl group); 22 straight-chain or branched aliphatic hydrocarbon groups (such as alkyl groups and alkenyl groups), or a hydroxylalkyl group having 2 to 10 carbon atoms.

The aliphatic hydrocarbon group may be saturated or unsaturated, and a saturated aliphatic hydrocarbon group is preferred.
Straight chain aliphatic hydrocarbon groups include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, octyl group, nonyl group, decyl group, dodecyl group, tetradecyl group, hexadecyl group, octadecyl group, Examples of the branched hydrocarbon group include an oleyl group and an isopropyl group and a 2-ethylhexyl group.

Among the above, at least one of R ¹ to R ³ has 1 to 16 carbon atoms, more preferably 6 to 16 carbon atoms, particularly 9 to 16 carbon atoms. When the number of carbon atoms is within the above range, the ammonium salt structure and the cellulose structure of cellulose nanocrystals (CNC) are well intertwined, and good antibacterial performance can be exhibited, which is preferable.

R ¹ and R ² may be the same or different.
From the viewpoint of maintaining long-term antibacterial properties, it is preferable that one or both of R ¹ and R ² are other than hydrogen atoms.
More preferably, the ammonium salt structure is a quaternary ammonium salt structure represented by the structure of general formula (1) above, in which both R ¹ and R ² are other than hydrogen atoms. In this case, (A) ammonium salt-modified nanocellulose is (A') ammonium salt-modified nanocellulose.

Examples of the hydroxylalkyl group include 2-hydroxyethyl group, 3-hydroxypropyl group, 2-hydroxyisopropyl group, and 6-hydroxyethyl group.

X ^- is a halogen ion, alkyl halide ion, alkyl carboxylate ion, nitroxide ion, alkyl sulfate ion, sulfonate ion, phosphate ion, or alkyl phosphate ion, and Y ^- is a carboxylate ion group, nitroxide Examples include ionic groups, alkyl sulfate ionic groups, sulfonate ionic groups, phosphate ionic groups, and alkyl phosphate ionic groups.

It is important that X ^- or Y ^- forms a stable salt with the ammonium cation in general formula (1) or general formula (2), and when X ^- or Y ^- has an alkyl group, The alkyl group may be covalently bonded to R ¹ , R ² or R ³ .

Next, the nanocellulose portion of the ammonium salt-modified nanocellulose will be explained.
Examples of the unmodified nanocellulose from which the nanocellulose portion is derived include long fibrous cellulose nanofibers (CNF) and highly crystalline cellulose nanocrystals (CNC). Cellulose nanocrystals are preferred from the viewpoint that even if they are added, the viscosity of the composition for forming a functional layer used during production is unlikely to increase, and the handling properties during application to the base layer are good.

From the viewpoint of improving the transparency of the functional layer, the average fiber diameter of nanocellulose is preferably 0.1 nm or more and 100 nm or less, more preferably 0.5 nm or more or 50 nm or less, and even more preferably 1 nm or more or 20 nm or less. preferable.
In addition, from the viewpoint of improving the transparency of the functional layer, the average fiber length of nanocellulose is preferably 1 nm or more and 1000 nm or less, more preferably 5 nm or more or 500 nm or less, and even more preferably 10 nm or more or 200 nm or less.
The average aspect ratio (fiber length/fiber diameter) of nanocellulose is preferably 1 or more and 500 or less, more preferably 10 or more or 200 or less, and even more preferably 20 or more or 100 or less. When the average aspect ratio is within the above range, the composition for forming a functional layer used during production is less likely to thicken and has good handling properties.
The average fiber diameter, average fiber length, and average aspect ratio of nanocellulose were determined by observing the fibers dispersed in the nanocellulose aqueous dispersion or in the coating liquid for forming a functional layer used during manufacturing using a scanning electron microscope, and It can be determined from the average value of selected and measured 100 or more pieces, more preferably 100 or more pieces.

A preferred embodiment of ammonium salt-modified nanocellulose includes ammonium salt-modified nanocellulose having repeating structural units represented by the following chemical formula (3).

In the formula, n is 0 to 15, preferably 5 to 15, more preferably 8 to 15.

Another preferred embodiment of ammonium salt-modified nanocellulose includes ammonium salt-modified nanocellulose having repeating structural units represented by the following chemical formula (4).

In the formula, n is 0 to 15, preferably 5 to 15, more preferably 8 to 15.

Ammonium salt-modified nanocellulose having repeating structural units represented by the above chemical formula (4) can be produced, for example, according to the description in the literature: J. Appl. Polym. Sci. 2017, 134, 44789.

[(B) Binder resin]
From the viewpoint of dispersion stability of (A) ammonium salt-modified nanocellulose in the functional layer, it is preferable to further use (B) a binder resin in the functional layer. Among these, water-soluble polymers are more preferable as the binder resin (B).
Examples of water-soluble polymers include polyester resin, acrylic resin, urethane resin, polyvinyl resin (polyvinyl alcohol resin, vinyl chloride vinyl acetate copolymer, etc.), polyalkylene glycol, polyalkylene imine, methylcellulose, hydroxycellulose. , starches, etc.
Among water-soluble polymers, polyvinyl alcohol resins or acrylic resins are preferred from the viewpoint of maintaining good antibacterial properties.

(Polyvinyl alcohol resin)
Polyvinyl alcohol resin (hereinafter sometimes abbreviated as PVA resin) is a resin mainly composed of vinyl alcohol structural units, which is obtained by saponifying polyvinyl ester resin obtained by polymerizing vinyl ester monomers. It is characterized by being composed of vinyl alcohol structural units and vinyl ester structural units corresponding to the degree of saponification.

The PVA-based resin is preferably a PVA-based resin having a crosslinked structure from the viewpoint of water resistance. Crosslinking agents for forming a crosslinked structure include dialdehyde compounds such as glyoxazal; methylol compounds such as dimethylol urea, trimethylol melamine, and dimethylol ethylene urea; epoxy compounds of epichlorohydrin; citric acid, polyacrylic Examples include carboxylic acid compounds such as acid, methyl vinyl ether-maleic acid copolymer, isobutylene-maleic anhydride copolymer, and thioglycolic acid; isocyanate compounds such as blocked isocyanate compounds; boron compounds such as boric acid and borax. Among these, citric acid is preferred from the viewpoint of antibacterial properties.

The degree of saponification of the PVA resin is preferably 40 mol% or more and 99 mol% or less, more preferably 40 mol% or more and 90 mol% or less, and still more preferably 50 mol% or more and 88 mol% or less. If the degree of saponification of the PVA-based resin is too low, it may be difficult to obtain the desired antibacterial performance; on the other hand, if the degree of saponification exceeds the upper limit, the stability of the functional layer composition may decrease. be.
Note that the saponification degree of PVA-based resin can be measured according to JIS K 6726:1994.

The average degree of polymerization of the PVA resin is 2,500 or less, preferably 2,000 or less. The lower limit is 100 or more, preferably 200 or more.
If the average degree of polymerization of the PVA-based resin is below the lower limit, it may become difficult to form a continuous functional layer. On the other hand, when the average degree of polymerization exceeds the upper limit, the viscosity of the composition for forming a functional layer is high, and coating streaks, coating unevenness, etc. tend to occur easily. Further, the average degree of polymerization of the PVA resin can be measured in accordance with JIS K 6726:1994.

(acrylic resin)
The acrylic resin is a polymer made of polymerizable monomers including (meth)acrylate monomers. These may be homopolymers, copolymers, or copolymers with polymerizable monomers other than (meth)acrylate monomers.
The above polymerizable monomer is not particularly limited. (Meth)acrylate monomers include hydroxyl group-containing (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; methyl (meth)acrylate , ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, lauryl (meth)acrylate, etc. meth)acrylate; sorbitol tri(meth)acrylate, sorbitol tetra(meth)acrylate, sorbitol penta(meth)acrylate, sorbitol alkylene oxide modified (meth)acrylate, pentaerythritol(meth)acrylate, polyethylene glycol diacrylate, neopentyl glycol diacrylate Examples include polyfunctional (meth)acrylates such as acrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, and tricyclodidecanedimethanol dimethacrylate.
Polymerizable monomers other than (meth)acrylate monomers include carboxyl group-containing polymerizable monomers such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid, citraconic acid, and their salts; Hydroxyl group-containing polymerizable monomers such as butyl hydroxy fumarate and monobutyl hydroxy itaconate; Nitrogen-containing polymerizable monomers such as (meth)acrylamide, diacetone acrylamide, N-methylol acrylamide, and (meth)acrylonitrile; styrene, α-methylstyrene , divinylbenzene, vinyltoluene, etc.; vinyl ester monomers such as vinyl propionate; silicon-containing polymerizable monomers such as γ-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane; phosphorus-containing vinyl polymerizable monomers halogenated vinyl monomers such as vinyl chloride and vinylidene chloride; and conjugated diene monomers such as butadiene.
Note that "(meth)acrylate" means acrylate or methacrylate.

It is preferable that the polymerizable monomer contains a polyfunctional (meth)acrylate.
Commercially available polyfunctional (meth)acrylates include Aronix M-933, Aronix M-926, Aronix MT-2518, and Aronix MT-2519 manufactured by Toagosei Co., Ltd.; Light Acrylate 9EG manufactured by Kyoeisha Chemical Co., Ltd. -A etc.

[Physical properties of functional layer]
The surface roughness Sa of the functional layer is preferably 50 nm or more, more preferably 100 nm or more, and particularly preferably 140 nm or more. The upper limit of the surface roughness Sa is not particularly limited, but is preferably 1000 nm or less, more preferably 500 nm or less.
If the surface roughness Sa of the functional layer is within the above range, the antiglare properties of the surface of the functional layer can be improved.
The surface uneven structure of the functional layer can be formed, for example, by a sol-gel reaction and phase separation between unmodified nanocellulose and an ammonium salt-containing compound that occur when forming the functional layer.
For example, after a reaction occurs between unmodified nanocellulose and an ammonium salt-containing compound, phase separation occurs within the functional layer coating due to hydrophobic interactions derived from alkyl groups, and a structure is formed in which the alkyl groups aggregate. Ru. In this case, since this structure is coarser than when the above-mentioned sol-gel reaction simply occurs, the surface becomes rough, and it can be considered that the anti-glare properties are good as a result.
In addition, when unmodified nanocellulose and an ammonium salt-containing compound undergo a dehydration condensation reaction, the proportion of hydroxyl groups in nanocellulose, that is, polar groups in the functional layer, decreases, which is thought to contribute to improving anti-glare properties as a functional layer. It will be done.

Note that the surface roughness Sa is defined in ISO 25178-2:2021, and specifically represents the arithmetic mean height, that is, the average of the absolute values of the differences in height of each point with respect to the average plane of the surface. . The surface roughness Sa can be measured using, for example, a scanning white interference microscope (“VertScan (registered trademark)” manufactured by Hitachi High-Tech Science Co., Ltd.).

The total light transmittance of the functional layer is preferably 85% or more, more preferably 90% or more, with an upper limit of 100%.
The haze of the functional layer is preferably 30% or less, more preferably 20% or less, and even more preferably 10% or less.

By having the total light transmittance and haze of the functional layer within the above ranges, the uneven structure of the surface increases the contact angle of water droplets, and the transparency of the surface protection film can be improved, so visibility is required. It can also be applied to various applications.
The total light transmittance and haze can be measured in accordance with JIS K 7136:2000 using a haze meter "HM-150" manufactured by Murakami Color Research Institute.

From the viewpoint of improving the strength of the coating film and preventing cracks, the thickness of the functional layer is preferably 10 nm or more and 1,000 nm or less, more preferably 50 nm or more and 500 nm or less, and even more preferably 100 nm or more and 300 nm or less.
Note that the above thickness is the thickness after drying.

2. Base Material Layer The material of the base material layer is not particularly limited, but is preferably a resin film, a fibrous base material, or glass.

Examples of resin films include polyolefin resins such as polyethylene and polypropylene; polyester resins such as polyethylene terephthalate (PET), polyethylene isophthalate, polyethylene naphthalate, and polybutylene terephthalate; polylactic acid; polyurethane; polyvinyl acetate; polyacrylonitrile ; Polyvinyl chloride; Films made of thermoplastic resins such as polycarbonate resins can be mentioned. The resin film may be a porous film that has been subjected to a porous treatment such as chemical foaming, physical foaming, or stretching, or a stretched film that has been subjected to a uniaxial or biaxial stretching treatment.
Among these, polyester films with good handling properties are preferred.

Examples of fibrous base materials include chemical fibers such as polyester fibers, nylon fibers, acrylic fibers, polyurethane fibers, acetate fibers, rayon fibers, and polylactic acid fibers; cotton, hemp, silk, wool, and blended fibers thereof. Examples include nonwoven fabrics, woven fabrics, knitted fabrics, etc.

The base material layer may have a single layer structure or a multilayer structure. In the case of a multilayer structure, it may be a two-layer structure, a three-layer structure, etc., or may be a multilayer structure of four or more layers without departing from the gist of the present invention, and the number of layers is not particularly limited. In the case of a multilayer structure, the plurality of layers may be made of the same resin or may be made of different resins.

Additives may be added to the base layer as necessary, such as ultraviolet absorbers for imparting weather resistance, and additives mainly for imparting slipperiness and preventing scratches in each process. It is also possible to incorporate particles. Furthermore, conventionally known antioxidants, antistatic agents, heat stabilizers, lubricants, dyes, pigments, etc. can be added as necessary.

The surface of the base layer on which the functional layer is formed may be subjected to surface treatment such as corona treatment, plasma treatment, or coating treatment for adjusting wettability.
The thickness of the base material layer is not particularly limited. For example, when the base material layer is a resin film, the thickness is preferably 9 μm or more and 250 μm or less, more preferably 12 μm or more and 188 μm or less, particularly 25 μm or more and 125 μm or less.

3. Adhesive Layer In the surface protection film of the present invention, it is necessary to provide an adhesive layer on the opposite side of the base layer to the functional layer. The adhesive layer is preferably an acrylic adhesive layer, a urethane adhesive layer, or a silicone adhesive layer.

(Silicone adhesive layer)
The silicone adhesive constituting the silicone adhesive layer may be any adhesive whose main component is silicone.
The "main component resin" refers to the resin with the largest content (mass) among the resins constituting the adhesive.
Examples of the silicone adhesive include addition reaction type, peroxide curing type, and condensation reaction type silicone adhesives. Among these, addition reaction type silicone pressure-sensitive adhesives are preferably used from the viewpoint of being curable at low temperatures and in a short time. Note that these addition reaction type silicone pressure-sensitive adhesives are cured when forming the pressure-sensitive adhesive layer on the support. When an addition reaction type silicone adhesive is used as the silicone adhesive, the silicone adhesive may contain a catalyst such as a platinum catalyst.
For example, addition-reactive silicone adhesives are produced by diluting a silicone resin solution with a solvent such as toluene as necessary, adding a catalyst such as a platinum catalyst, stirring the mixture to make it uniform, and then coating it on a support. For example, it can be cured at a curing temperature of 100 to 130° C. and a curing time of 1 to 5 minutes. Further, if necessary, a crosslinking agent and an additive for controlling adhesive strength may be added to the addition reaction type silicone pressure-sensitive adhesive, or the base film may be subjected to a primer treatment before forming the pressure-sensitive adhesive layer.

Commercially available silicone resins used in addition reaction silicone adhesives include, for example, SD4580PSA, SD4584PSA, SD4585PSA, SD4587LPSA, SD4560PSA, SD4570PSA, SD4600FCPSA, SD4593PSA, DC7651ADHESIVE, D C7652ADHESIVE, LTC-755, LTC-310 (all Toray Dow Corning), KR-3700, KR-3701, KR-3704, X-40-3237-1, X-40-3240, X-40-3291-1, X-40-3229, X-40- 3323, X-40-3306, X-40-3270-1 (all manufactured by Shin-Etsu Chemical Co., Ltd.), AS-PSA001, AS-PSA002, AS-PSA003, AS-PSA004, AS-PSA005, AS-PSA012 , AS-PSA014, PSA-7465 (all manufactured by Arakawa Chemical Industries, Ltd.), TSR1512, TSR1516, TSR1521 (all manufactured by Momentive Performance Materials), and the like.

The thickness of the silicone adhesive layer is preferably 1 to 100 μm, more preferably 5 to 80 μm, even more preferably 10 to 60 μm, and even more preferably 20 to 50 μm.
Note that the above thickness is the thickness after drying.

(Acrylic adhesive layer)
The acrylic adhesive layer contains a (meth)acrylic ester (co)polymer and, if necessary, further contains a photopolymerization initiator, a crosslinking agent, a silane coupling agent, and other materials. It can be formed from a composition for use. The acrylic adhesive layer can be formed from a conventionally known composition for forming an adhesive layer, and for example, the composition for forming an adhesive layer described in JP 2019-210446A and the like may be used.

<Urethane adhesive>
As the urethane base polymer of the urethane adhesive, a reaction product of a polyol and a polyisocyanate compound can be used.
Examples of the polyol component include polymer type polyols such as polyester polyol, polyether polyol, polycarbonate polyol, and caprolactone polyol. These polyol components may be used alone or in combination of two or more.
Examples of the polyisocyanate compound include aliphatic polyisocyanates, alicyclic polyisocyanates, and aromatic polyisocyanates. These polyisocyanate compounds may be used alone or in combination of two or more.

The thickness of the adhesive layer is preferably 1 to 100 μm, more preferably 5 to 80 μm, even more preferably 10 to 60 μm, particularly preferably 20 to 50 μm.
The above thickness is the thickness after drying.

4. Other Layers The surface protection film may include layers other than the functional layer and the base layer. For example, another layer may be further provided between the functional layer and the base material layer, or on the side of the base material layer opposite to the functional layer.
Examples of other layers include a primer layer, a release layer, and a stress relaxation layer for improving the adhesion between the base material and the functional layer.

(Primer layer)
Examples of the primer layer include a primer layer containing a polyvalent cation resin.
By providing a primer layer containing a polyvalent cation resin as an undercoat layer for the functional layer, a mixed state in which the polyvalent cation resin naturally diffuses and intervenes between the nanocellulose in the functional layer can be expected, and furthermore, the functional layer and the base layer are The effect of improving adhesion with the material layer can be expected.
The polyvalent cationic resin used in the present invention is a resin that is water-soluble or water-dispersible and contains a polyvalent cationic functional group, that is, two or more cationic functional groups. An example of the cationic functional group is an amino group.
Specific examples of polyvalent cation resins include water-soluble amino group-containing polymers such as polyethyleneimine, polyallylamine, polyamine polyamide epichlorohydrin, polyamine epichlorohydrin, polyacrylamide, poly(diallyldimethylammonium salt), and dicyandiamide formalin. , poly(meth)acrylate, cationized starch, cationized gum, chitosan, and the like. Among these, water-soluble amine-containing polymers are preferred, and polyethyleneimine is more preferred. Specific examples of polyethyleneimine include branched polyethyleneimine.
The thickness of the primer layer is not particularly limited. For example, the thickness is preferably 0.1 μm or more and 10 μm or less, more preferably 0.5 μm or more and 8 μm or less, particularly 1 μm or more and 5 μm or less.

(Release layer)
When the adhesive layer is an acrylic adhesive layer, a silicone adhesive layer, or a urethane adhesive layer, the surface protection film may further include a release layer.
Examples of the release layer include a type containing a curable silicone resin as a main component; a modified silicone resin type formed by graft polymerization with an organic resin such as a urethane resin, an epoxy resin, and an alkyd resin; and a fluorosilicone resin.

As the curable silicone resin, any existing curing reaction type can be used, such as thermosetting types such as addition type and condensation type; electron beam curing types such as ultraviolet curing type; and the like.
One type of curable silicone resin may be used alone, or two or more types may be used in combination.

There are no restrictions on the type of curable silicone resin. From the viewpoint of excellent mold release properties such as easy peelability, curable silicone resins containing alkenyl groups are preferred. The curable silicone resin containing an alkenyl group is preferably a diorganopolysiloxane, and more preferably a compound represented by the following general formula (5).
R ¹¹ _(3-a) W _a SiO-(R ¹¹ WSiO) _p -(R ¹¹ ₂ SiO) _q -SiW _a R ¹¹ _(3-a) ...(5)

In the above general formula (5), R ¹¹ is a monovalent hydrocarbon group having 1 to 10 carbon atoms, and W is an alkenyl group-containing organic group. a is an integer from 0 to 3, preferably 1. p is 0 or more, and p and q are numbers that each satisfy 100≦p+q≦20000. However, when a=0, p is 2 or more. Moreover, the above general formula (5) is not limited to block copolymers. In other words, in the compound represented by the above general formula (5), p constituent units -(R ¹¹ WSiO)- and q constituent units -(R ¹¹ ₂ SiO)- are arranged randomly on the main chain. It may also be a random copolymer.

Specifically, R ¹¹ includes an alkyl group having 1 to 10 carbon atoms such as a methyl group, ethyl group, propyl group, butyl group, a cycloalkyl group having 3 to 10 carbon atoms such as a cyclohexyl group, a phenyl group, and tolyl group. Examples include aryl groups having 6 to 10 carbon atoms, with methyl and phenyl groups being particularly preferred.
W is preferably an organic group having 2 to 10 carbon atoms containing an alkenyl group, specifically vinyl group, allyl group, hexenyl group, octenyl group, acryloylpropyl group, acryloylmethyl group, methacryloylpropyl group, cyclohexenyl group. Examples include ethyl group and vinyloxypropyl group, with vinyl group and hexenyl group being particularly preferred.
A specific example of the curable silicone resin represented by the above general formula (5) is a dimethylsiloxane/methylhexenylsiloxane copolymer blocked with trimethylsiloxy groups at both ends of the molecular chain (for example, 96 mol% dimethylsiloxane units, methylhexenylsiloxane Dimethylsiloxane/methylhexenylsiloxane copolymer (e.g., 97 mol% dimethylsiloxane units, 3 mol% methylhexenylsiloxane units), dimethylhexenylsiloxane copolymer blocked with dimethylvinylsiloxy groups at both molecular chain ends), dimethylhexenylsiloxy at both molecular chain ends A group-blocked dimethylsiloxane/methylhexenylsiloxane copolymer (for example, 95 mol% dimethylsiloxane units, 5 mol% methylhexenylsiloxane units) is exemplified.

The release layer is preferably a layer formed by curing a silicone resin composition containing the above-mentioned curable silicone resin and a crosslinking agent capable of curing the curable silicone resin. Examples of the crosslinking agent used in the release layer include polyorganosiloxane containing SiH groups.
A polyorganosiloxane containing an SiH group can react with, for example, a curable silicone resin containing an alkenyl group to form a stronger silicone release layer. Examples of polyorganosiloxanes containing SiH groups include organohydrogenpolysiloxanes having preferably two or more, more preferably three or more hydrogen atoms bonded to silicon atoms in one molecule. The molecular shape of the polyorganosiloxane containing SiH groups may be linear, branched, cyclic, or the like. Preferred polyorganosiloxanes containing SiH groups include, but are not limited to, compounds represented by the following general formula (6).
H _b R ¹² _(3-b) SiO-(HR ¹² SiO) _x -(R ¹² ₂ SiO) _y -SiR ¹² _(3-b) H _b ...(6)

In the above general formula (6), R ¹² is a monovalent hydrocarbon group having 1 to 6 carbon atoms and containing no aliphatic unsaturated bond. b is an integer from 0 to 3, and x and y are each integers.

Specific examples of the compound represented by the above general formula (6) include methylhydrogenpolysiloxane with trimethylsiloxy group-blocked at both molecular chain ends, dimethylsiloxane/methylhydrogensiloxane copolymer with trimethylsiloxy group-blocked at both molecular chain ends, Examples include methylhydrogenpolysiloxane with dimethylhydrogensiloxy groups endblocked at both molecular chain ends, and dimethylsiloxane/methylhydrogensiloxane copolymer endblocked with dimethylhydrogensiloxy groups at both molecular end ends.
The molar ratio of Si-H groups to alkenyl groups ([Si-H groups]/[alkenyl groups]) in the curable silicone resin composition is preferably 0.1 to 2.0, and preferably 0.2 to 1. It is more preferably .9, and even more preferably 0.3 to 1.8.

Commercially available curable silicone resins include KS-774, KS-775, KS-778, KS-779H, KS-847H, KS-856, X-62-2422, and X-62 manufactured by Shin-Etsu Chemical Co., Ltd. -2461, X-62-1387, X-62-5039, X-62-5040, KNS-3051, X-62-1496, KNS320A, KNS316, -62-7028A/B, X-62-7619, X-62-7213, X-41-3035; YSR-3022, TPR-6700, TPR-6720, TPR-6721, TPR6500 manufactured by Momentive Performance Materials , TPR6501, UV9300, UV9425, A, LTC760A, LTC303E, LTC856, LTC761, SP7259, BY24-468C, SP7248S, BY24-452, DKQ3-202, DKQ3-203, DKQ3-204, DKQ3-205, DKQ3-210; DEHESIVE 636, DEHESIVE 919, D manufactured by Asahi Kasei Wacker Silicone Co., Ltd. EHESIVE 920, DEHESIVE 921, DEHESIVE 924, DEHESIVE 929, etc.

The release layer preferably contains a platinum-based catalyst that promotes addition-type reactions. Therefore, it is preferable that the silicone resin composition further contains a platinum-based catalyst. Examples of platinum-based catalysts include platinum-based compounds such as chloroplatinic acid, alcoholic solutions of chloroplatinic acid, complexes of chloroplatinic acid and olefins, complexes of chloroplatinic acid and alkenylsiloxane, platinum black, platinum-supported silica, and platinum-supported silica. Activated carbon etc. are exemplified.
The platinum catalyst content in the release layer is preferably 0.01 to 10.0% by mass, more preferably 0.01 to 5.0% by mass. When the platinum-based catalyst content in the release layer is 0.01% by mass or more, sufficient peeling force is obtained, the curing reaction progresses sufficiently, and problems such as deterioration of the surface condition do not occur. On the other hand, if the content of the platinum-based catalyst in the release layer is 3.0% by mass or less, it is not only advantageous in terms of cost, but also increases reactivity and does not cause process defects such as generation of gel foreign matter.

The release layer is formed by coating a film with a composition for forming a release layer. It may be provided by in-line coating performed within the film forming process, or so-called off-line coating, in which it is applied outside the system on the adhesive layer once produced, may be employed.

As a method for providing a release layer on the adhesive layer, conventionally known coating methods such as reverse gravure coating, direct gravure coating, roll coating, die coating, bar coating, curtain coating, etc. can be used.

There is no particular restriction on the form of the composition for forming a mold release layer, and it may be in any form, such as a form dissolved in an organic solvent, an aqueous emulsion form, or a non-solvent form.
The release forming layer composition may contain an antifoaming agent, a coating property improver, a thickener, an inorganic/organic particle, an organic lubricant, an antistatic agent, a conductive agent, an ultraviolet absorber, Antioxidants, blowing agents, dyes, pigments, etc. may also be contained.

There are no particular limitations on the curing conditions when forming the mold release layer, and when forming the mold release layer by off-line coating, it is usually cured at 80°C or higher for 10 seconds or more, preferably at 100 to 200°C for 3 to 40 seconds. The heat treatment is preferably carried out at 120 to 180° C. for 3 to 40 seconds. Further, heat treatment and active energy ray irradiation such as ultraviolet ray irradiation may be used in combination as necessary. Note that as an energy source for curing by active energy ray irradiation, known devices and energy sources can be used.

The thickness of the release layer is usually 0.005 μm or more and 3.0 μm or less, preferably 0.01 μm or more and 1.0 μm or less, more preferably 0.03 μm or more and 0.5 μm or less, and even more preferably 0.05 μm or more and 0.3 μm. It is as follows. When it is 0.005 μm or more, coating properties are excellent and a uniform coating film can be stably obtained. On the other hand, if it is 3.0 μm or less, the film adhesion and curability of the release layer itself will not deteriorate, which is preferable.
The above thickness is the thickness after drying.

5. Antibacterial properties This surface protection film has antibacterial properties.
In one preferred embodiment, the surface protection film has an antibacterial activity value of 3 or more for E. coli after being irradiated with ultraviolet light of 340 to 400 nm at 60 W/m ² for 10 hours.
In another preferred embodiment, the surface protection film has an antibacterial activity value of 3 or more against Staphylococcus aureus after being irradiated with ultraviolet light of 340 to 400 nm at 60 W/m ² for 10 hours.
The antibacterial activity value is calculated according to JIS Z2801:2010.

<Method for manufacturing base material with functional layer constituting surface protection film>
Next, a method for manufacturing a base material with a functional layer constituting a surface protection film according to an example of an embodiment of the present invention will be described.

[First manufacturing method]
The first method for producing the base material with a functional layer constituting the present surface protection film is to prepare a coating solution consisting of the present functional layer forming composition containing unmodified nanocellulose and an ammonium salt-containing compound. a coating film forming step of applying the coating solution to the surface of the base material layer to form a coating film, and heating the coating film to obtain a functional layer containing quaternary ammonium salt-modified nanocellulose. It includes a treatment step and/or an active energy ray treatment step.
Note that, as long as the first manufacturing method of the present functional layer-attached base material includes the above-mentioned steps, it is possible to add other treatments or steps as desired.

Furthermore, in the present invention, a "process" may or may not be performed on a series of production lines. Further, the processing in one step may be performed intermittently, and in that case, the processing may be performed intermittently by changing the equipment, changing the location, etc. Moreover, it may be performed in a series of manufacturing lines with other steps. That is, a plurality of steps may be performed using the same device.

1. Coating Solution Preparation Step In the coating solution preparation step, unmodified nanocellulose and an ammonium salt-containing compound are mixed in a solvent to prepare a coating solution comprising a composition for forming a functional layer.

[Composition for forming functional layer]
The composition for forming a functional layer contains the unmodified nanocellulose, the ammonium salt-containing compound, and a solvent, and further contains the binder resin (B) and the additive (C) as necessary.
As the binder resin (B), the functional layer forming composition includes (B) the binder resin itself, or (B) a monomer or oligomer (hereinafter also referred to as monomer etc.) that can form the binder resin. , a crosslinking agent, a polymerization initiator, and the like.
(B) When the binder resin is a polyvinyl alcohol resin, the composition for forming a functional layer preferably contains a monomer and the like and an aqueous crosslinking agent such as citric acid as a crosslinking agent. The water-based crosslinking agent is preferably one that performs crosslinking through dehydration condensation.
(B) When the binder resin is an acrylic resin, the composition for forming a functional layer preferably contains a monomer etc. and a polymerization initiator. Examples of the polymerization initiator include photopolymerization initiators, thermal polymerization initiators, and the like.

(Ammonium salt-containing compound)
The ammonium salt-containing compound is not limited as long as it is a compound that can introduce the above ammonium salt structure into unmodified nanocellulose. The ammonium salt-containing compound is preferably a quaternary ammonium salt-containing compound. Specific examples of quaternary ammonium salt-containing compounds include quaternary ammonium salt-containing silane coupling agents.
Commercial products of silane coupling agents containing quaternary ammonium salts include KBM-9418-40, X-12-1126, and X-12-1139 manufactured by Shin-Etsu Chemical Co., Ltd.; Biosafe Antimicrobials series manufactured by Gelest; Examples include HE4001, HE4005, HM4005, HM4072, HM4100, and the like.

(C) Additives Examples of additives that may be included in the composition for forming a functional layer, if necessary, include acidic substances or basic substances for pH adjustment. As the acidic substance, for example, citric acid may be used in combination with the expectation of improving the water resistance of the functional layer. Examples of the basic substance include ammonia and the like.

(solvent)
The composition for forming a functional layer contains a solvent.
The solvent may be, for example, water, alcohol, or a mixture thereof (hereinafter collectively referred to as (also referred to as "water/alcoholic solvent") is preferred.

When water/alcoholic solvent is used as a solvent, water is preferably 15% by mass or more and 75% by mass or less in 100% by mass of the solvent, and more preferably 30% by mass or more or 50% by mass or less.
Examples of the alcohol in the water/alcohol solvent include methanol, ethanol, and the like.
When the water content is at least the above lower limit, the unmodified nanocellulose has good dispersibility and is less likely to aggregate. On the other hand, when the water content is at most the above upper limit, it becomes easier to control the condensation reaction of the ammonium salt-containing compound.

(Content of each component)
The content of unmodified nanocellulose in the composition for forming a functional layer is preferably 0.1% by mass or more and 5% by mass or less, and more preferably 0.2% by mass or more and 3% by mass or less. When the content of unmodified nanocellulose is within the above range, the coating amount can be easily controlled and the viscosity is less likely to increase, resulting in good handling properties during coating on the base layer.

Further, the content of the ammonium salt-containing compound in the composition for forming a functional layer is preferably 1% by mass or more and 20% by mass or less, and more preferably 2% by mass or more and 10% by mass or less. When the ammonium salt content is within the above range, pot life and coating method selectivity are improved.

Furthermore, the mass ratio of unmodified nanocellulose to ammonium salt-containing compound in the composition for forming a functional layer (unmodified nanocellulose/ammonium salt-containing compound) is preferably 5/95 to 40/60, and 10/90 to 30/70 is more preferred. When the content mass ratio is within the above range, gelation due to condensation reaction between ammonium salt-containing compounds is unlikely to occur, and the reaction between unmodified nanocellulose and ammonium salt-containing compounds proceeds well, resulting in water repellency. Become good.

[Preparation method]
From the viewpoint of increasing the dispersibility of nanocellulose in the coating liquid, it is preferable to disperse unmodified nanocellulose in a solvent and then add the ammonium salt-containing compound. When adjusting the pH, it is preferable that a basic substance be added in this step.
After mixing the unmodified nanocellulose and the ammonium salt-containing compound, heating may be performed to increase reactivity. Although a reaction occurs even when unmodified nanocellulose and an ammonium salt-containing compound are simply mixed, the reaction can be accelerated by heating.
The heating temperature and heating time may be any conditions as long as the reaction between the unmodified nanocellulose and the ammonium salt-containing compound proceeds. For example, the heating temperature is preferably 30°C or higher and 80°C or lower, particularly 40°C or higher and 70°C or higher. It is more preferable that the temperature is below ℃. The heating time is preferably 30 seconds or more and 2 hours or less, and more preferably about 30 minutes or more and 1 hour or less.
After the heating, the mixture may be cured at room temperature for 1 to 7 days in order to further advance the reaction of the ammonium salt-containing compound.

The mass ratio of the added amounts of nanocellulose and ammonium salt-containing compound (nanocellulose/ammonium salt-containing compound) is preferably 5/95 to 40/60, more preferably 10/90 to 30/70. By being within the above range, gelation due to condensation reaction between ammonium salt-containing compounds is unlikely to occur, and the reaction between nanocellulose and ammonium salt compounds proceeds well, resulting in good anti-glare properties on the surface of the functional layer. Become.

2. Coating Film Forming Step In the coating film forming step, the above coating liquid is applied to the surface of the base material layer to form a coating film.
The method of applying the coating liquid to the base material layer may be a known method, such as a comma coating method, a gravure coating method, a reverse coating method, a knife coating method, a dip coating method, a spray coating method, an air knife coating method, Examples include spin coating, roll coating, printing, dipping, slide coating, curtain coating, die coating, casting, bar coating, extrusion coating, and the like.
The thickness of the coating film is preferably 10 nm or more and 10,000 nm or less, more preferably 500 nm or more and 5000 nm or less. When the thickness of the coating film is equal to or greater than the above lower limit, control during coating becomes easier. When the thickness of the coating film is less than or equal to the above upper limit, cracks due to shrinkage during drying are less likely to occur.

3. Heat treatment process In the heat treatment process, the reaction of introducing an ammonium salt structure into unmodified nanocellulose is efficiently progressed by heat treatment, and the solvent is removed from the coating film to form the functional layer containing ammonium salt modified nanocellulose. form.

The heating method may be a known method.
The heating temperature and heating time are preferably such that the solvent is removed from the coating film and the introduction of the ammonium salt structure into the unmodified nanocellulose progresses well. For example, the heating temperature is 60°C or higher and 150°C or higher. The temperature is preferably 80°C or higher and 120°C or lower, particularly preferably 80°C or higher and 120°C or lower. The heating time is preferably 30 seconds or more and 5 hours or less, and more preferably 30 minutes or more and about 2 hours or less.

4. Active energy ray treatment step For example, when the composition for forming a functional layer contains a photopolymerization initiator, active energy rays that can be used to cure the composition for forming a functional layer include ultraviolet rays, electron beams, and X-rays. , infrared and visible light. Among the active energy rays, ultraviolet rays or electron beams are preferred from the viewpoint of curability and prevention of resin deterioration.
The method for curing the composition for forming a functional layer is preferably curing by irradiation with active energy rays, from the viewpoint of molding time and productivity, and from the viewpoint of preventing thermal shrinkage and thermal deterioration of each member due to heating. The energy ray irradiation may be performed from either side, from the base film side, or from the opposite side of the base film.
When producing the functional layer-attached base material of the present invention and curing the composition for forming a functional layer by irradiating ultraviolet rays, various types of ultraviolet irradiation equipment can be used, and the light sources include xenon lamps, high-pressure mercury lamps, Metal halide lamps, LED-UV lamps, etc. can be used. The amount of ultraviolet ray irradiation (unit: mJ/cm ² ) is usually 50 mJ/cm ² or more and 3,000 mJ/cm ² or less, and is effective for curability of the functional layer forming composition, performance development of the functional layer (cured film), etc. From the viewpoint of this, it is preferably 100 mJ/cm ² or more and 1,000 mJ/cm ² or less, more preferably 200 mJ/cm ² or more and 1000 mJ/cm ² or less, for forming a functional layer required in each curing step. It is determined as appropriate depending on the reaction rate of the composition.

[Second manufacturing method]
The second method for producing a base material with a functional layer includes a first coating step of applying a first coating liquid containing a polyvalent cation resin onto the surface of the base material layer, unmodified nanocellulose, and an ammonium salt-containing compound. A second coating step of applying a second coating solution comprising a composition for forming a functional layer containing a functional layer forming composition onto the surface of the coating film of the first coating solution, and heating the coating film to form an ammonium salt-modified nanocellulose. A heat treatment step and/or an active energy ray treatment step for obtaining a functional layer containing.
In addition, in the second manufacturing method of the base material with a functional layer, the above order is preferable from the viewpoint of adhesiveness between the functional layer containing ammonium salt-modified nanocellulose and the base material layer.
Further, as long as the above steps are provided, it is possible to add other treatments or steps as desired.

1. First Coating Step In the first coating step, a first coating liquid containing a polyvalent cation resin is applied to the surface of the base layer.
Preferably, the first coating liquid contains a polyvalent cation resin in a solvent. The content of the polyvalent cation resin is preferably 5% by mass or more and 80% by mass or less, more preferably 10% by mass or more and 50% by mass or less.
As the solvent, the above-mentioned water/alcohol solvents can be used.
The thickness of the coating film is preferably 10 nm or more and 1000 nm or less, more preferably 30 nm or more and 300 nm or less.
The method of applying the first coating liquid to the base material layer may be a known method, such as a comma coating method, a gravure coating method, a reverse coating method, a knife coating method, a dip coating method, a spray coating method, and an air knife method. Examples include a coating method, a spin coating method, a roll coating method, a printing method, a dip method, a slide coating method, a curtain coating method, a die coating method, a casting method, a bar coating method, an extrusion coating method, and the like.
After applying the first coating liquid to the base layer, heating may be performed. The heating temperature and heating time may be any condition as long as the solvent is removed from the coating film. For example, the heating temperature is preferably 60°C or more and 150°C or less, and particularly preferably 80°C or more and 120°C or less. More preferred. The heating time is preferably 10 seconds or more and 1 hour or less, and more preferably 30 seconds or more and about 30 minutes or less.

2. Second coating process The second coating process is the same as the coating film forming process in the first production method above, except that a coating film is formed on the coating surface of the first coating liquid instead of on the base layer surface. It can be done by

3. Heat Treatment Step In the heat treatment step, the coating film is dried by heat treatment to form the main functional layer.
The drying method, drying temperature, and drying time may be the same as the heat treatment step in the first manufacturing method.

4. Active energy ray treatment step Active energy rays that can be used to cure the functional layer composition of the present invention include ultraviolet rays, electron beams, X-rays, infrared rays, and visible rays. Among these active energy rays, ultraviolet rays and electron beams are preferred from the viewpoint of curability and prevention of resin deterioration.
As the method for curing the functional layer composition, curing by energy ray irradiation is preferred from the viewpoint of molding time and productivity, and from the viewpoint of preventing thermal shrinkage and thermal deterioration of each member due to heating. The energy ray irradiation may be performed from either side, from the base film side, or from the opposite side of the base film.
When producing the surface protection film of the present invention, when curing the functional layer composition by irradiating ultraviolet rays, various types of ultraviolet irradiation equipment can be used, and the light sources include xenon lamps, high-pressure mercury lamps, metal halide lamps, and LEDs. - UV lamps etc. can be used. The amount of ultraviolet ray irradiation (unit: mJ/cm ² ) is usually 50 mJ/cm ² or more and 3,000 mJ/cm ² or less, from the viewpoint of curability of the functional layer composition, performance development of the functional layer (cured film), etc. , preferably 100 mJ/cm ² or more and 1,000 mJ/cm ² or less, more preferably 200 mJ/cm ² or more and 1000 mJ/cm ² or less, depending on the reaction of the functional layer composition required in each curing step. It will be determined as appropriate depending on the rate.

<Method for manufacturing surface protection film>
The surface protection film of the present invention can be prepared, for example, by using the above-mentioned base material with a functional layer and applying an adhesive layer-forming composition to the surface of the base material layer on the side opposite to the side on which the functional layer is provided. A surface protection film can be obtained through a coating film forming process, a heat treatment process and/or an active energy ray treatment process in which the coating film is heat-treated to obtain an adhesive layer.
When the surface protection film of the present invention has a release layer, the surface protection film can also be obtained by manufacturing a release film with an adhesive layer in advance and laminating the release film with an adhesive layer and the above-mentioned base material with a functional layer. be able to.
Specifically, there is a coating film forming step in which a composition for forming an adhesive layer is applied to the surface of the release layer of a release film to form a coating film, and a heat treatment in which the coating film is heat-treated to form an adhesive layer. A release film with an adhesive layer is obtained by a method that includes a process and/or an active energy ray treatment process.
Furthermore, through the process of laminating the surface of the base film with a functional layer on which no functional layer is provided on the surface of the adhesive layer of the release film with an adhesive layer, the structure of the functional layer/base film/adhesive layer/release film is completed. A surface protection film which is a laminate consisting of the following can be obtained.
Note that conventionally known methods can be used for the step of forming the adhesive layer and the step of laminating the functional layer-attached base film to the adhesive layer.

<Application>
Since the surface protection film of the present invention has excellent UV resistance and halogen resistance, it can be suitably used for various exterior and interior materials, separation membranes, and the like. Examples include building materials such as walls and roofs of architectural structures, general residences, and public facilities; interior and exterior parts of vehicles such as cars, trains, ships, and airplanes; parts for home appliances; signboards, signs, etc.
The surface protection film of the present invention is suitable for use in protecting the surface of a device whose surface is used by touching the surface multiple times with a fingertip, whether indoors or outdoors. Among these, it can be suitably used to protect the display surface of a smart mirror, especially a smart mirror with a relatively large screen.
A smart mirror is a device that has both a display function for displaying information such as text, images, and videos output from a computer, and a mirror function for projecting a mirror image. A smart mirror can obtain and display information such as weather, news, etc. through an Internet connection, for example. An example of a relatively large-area smart mirror is a life-size mirror with one side of 500 mm or more and the other side of 1000 mm or more. The display surface of the smart mirror is made of glass or highly transparent resin, for example, and is preferably made of glass.
In addition, since the surface protection film exhibits high UV resistance and halogen resistance in raw materials based on non-depletable resource materials, it can be applied as various functional materials. It is also known that by selecting an appropriate composition, it is possible to impart high transparency or anti-glare properties, making it possible to apply it to applications that require visibility or anti-glare properties. .
The present invention also relates to a film laminate in which a surface protection film is bonded to the above adherend.

<Explanation of words>
In the present invention, when expressed as "X to Y" (X, Y are arbitrary numbers), unless otherwise specified, it means "more than or equal to X and less than or equal to Y", and also means "preferably greater than It also includes the meaning of "small".
In addition, when expressed as "more than or equal to X" (X is any number) or "less than or equal to Y" (Y is any number), the expression "preferably greater than X" or "preferably less than Y" should be used. It also includes intent.

Hereinafter, the surface protection film of the present invention will be described in more detail based on Examples. Note that the surface protection film of the present invention is not limited in any way by the following Examples and Comparative Examples.

<Evaluation method>
(1) Measurement of thickness of functional layer The surface protection films obtained in Examples and Comparative Examples were cut in the thickness direction, and the cut surfaces were examined using a scanning white interference microscope (VertScan (registered trademark) manufactured by Hitachi High-Tech Science Co., Ltd.). )") to measure the thickness of the functional layer.

(2) Measurement of water droplet contact angle For each surface protection film obtained in Examples and Comparative Examples, the water droplet contact angle on the surface of the functional layer was measured using a contact angle meter (Drop Master 500, manufactured by Kyowa Chemical Co., Ltd.). .

(3) Measurement of surface roughness Sa The surface roughness Sa (ISO 25178-2:2021) of the functional layer of each surface protection film obtained in Examples and Comparative Examples was measured using a scanning white interference microscope (Mitsubishi Chemical System Co., Ltd. It was measured using "VertScan (registered trademark)" manufactured by ).

(4) Measurement of total light transmittance and haze In accordance with JIS K 7136:2010, each function obtained in Examples and Comparative Examples using a haze meter “HM-150” manufactured by Murakami Color Research Institute Co., Ltd. The total light transmittance and haze of the layered base film were measured.

(5) Antibacterial test According to JIS Z 2801:2010, Escherichia coli and Staphylococcus aureus were used as test bacteria. The number of viable bacteria (CFU/mL) after 24 hours of culture was counted, and the antibacterial activity value was calculated.
The antibacterial activity value is a test method defined in the antibacterial test method described in JIS Z 2801:2010, and is an index value for determining the degree of antibacterial effect. Specifically, it is calculated as the logarithm of the number of bacteria after 24-hour culture (B) of the unprocessed product divided by the number of bacteria after 24-hour culture (C) of the antibacterial processed product.
The base film with each functional layer obtained in the Examples and Comparative Examples was used as an antibacterial processed product, and only the biaxially stretched polyester film as the base material was used as an unprocessed product.
In addition, if the antibacterial activity value was 3 or more, it was determined that it was at a practically usable level.

(6) UV resistance test Using a Super Irradiation was performed for 10 hours at an output of 60 W/m ² , and haze measurements and antibacterial tests were performed on each evaluation sample after irradiation.
For haze, the rate of change before and after UV irradiation was calculated.

(7) Halogen resistance test: Sodium hypochlorite aqueous solution wiping test Using a friction fastness tester RT-300 (manufactured by Daiei Kagaku Seiki Seisakusho Co., Ltd.), each surface protection film obtained in Examples and Comparative Examples was tested. 1.0 g of sodium hypochlorite aqueous solution with an effective chlorine concentration of 0.5% was dropped onto the functional layer surface, and a clean room wiper (manufactured by Hashimoto Cross Co., Ltd., Super Clean N2325) was rubbed 10 times with a load of 200 g. . After the wiping test, each evaluation sample was subjected to a visual evaluation of appearance and an antibacterial test based on the following criteria.
(Judgment criteria)
○: The transparency of the coating film remains after the test.
×: Appearance changes such as cloudiness or membrane rupture after the test.

(8) Anti-glare test Each surface protection film obtained in Examples and Comparative Examples was coated with black tape (Scotch electrical insulation grade, manufactured by 3M) on the base material surface (back surface) opposite to the side on which the functional layer was provided. Vinyl tape 117) was attached, the surface of the film was irradiated with a fluorescent lamp, and the extent to which the reflected light became blurred was evaluated using the following criteria.
(Judgment criteria)
A: The outline of the fluorescent light becomes completely blurred.
B: Fluorescent light makes the image blurry, but the outline remains.
C: The outline of the fluorescent light is clearly visible.

(9) Glare test The functional layer side of the evaluation sample was pasted on the display of a tablet PC (Apple iPad (MW6C2J/A) series) displaying a green image, and the glare was visually checked from the display using the following methods. Evaluation was made according to the criteria.
A: Color unevenness due to glare is not observed, and good display visibility is maintained.
B: Slight color unevenness due to glare is observed, and the visibility of the display is reduced.
C: Color unevenness due to glare is clearly observed, and the visibility of the display is significantly reduced.

(Base material)
Biaxially oriented polyester film (PET) (manufactured by Mitsubishi Chemical Corporation, product name: "Diafoil (T600E type 50μm)")
(Composition for forming functional layer)
・(A) Quaternary ammonium salt modified cellulose nanocrystal A1: ・Cellulose nanocrystal (CNC) (manufactured by CelluForce, product name: NCV-100)
・Silane-based quaternary ammonium salt (manufactured by Shin-Etsu Chemical Co., Ltd., product name: X-12-1139)
・(B) Binder resin B1: ・PVA resin, PVA with saponification degree of 88 mol% and polymerization degree of 500 (manufactured by Mitsubishi Chemical Corporation)
B2: Polyethylene glycol diacrylate (PEDGA), number average molecular weight 526 (manufactured by Kyoeisha Chemical Co., Ltd., product name: Light Acrylate 9EG-A)
B3: EO-modified sorbitol acrylate (trifunctional acrylate) (manufactured by Toagosei Co., Ltd., product name: MT-2518)
・(C) Additives, etc. C1: Citric acid Weight average molecular weight 210 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
C2: Zeomic (Ag-based antibacterial agent, manufactured by Sinanen Zeomic Co., Ltd., product name: HW10N)
C3: Polymerization initiator: Omnirad (registered trademark) 2959 manufactured by IGM RESINS

(Primer layer)
・Polyethyleneimine (PEI), number average molecular weight 70,000, amine value 18 mmol/g solid, amine group molar ratio [primary amine 25%, secondary amine 50%, tertiary amine 25%] (Nihon Co., Ltd.) Made by Catalyst, Product Name: P-1000)

(Adhesive layer forming composition)
・(x1) (meth)acrylic copolymer,
Acrylic graft copolymer (x2 ) Crosslinking agent Tricyclodecane dimethacrylate (manufactured by Shin Nakamura Chemical Co., Ltd., product name: DCP)
・(x3) Photopolymerization initiator Irgacure 369 (manufactured by BASF)

(Release film)
Polyethylene terephthalate film (manufactured by Mitsubishi Chemical Corporation, Diafoil MRV, thickness 100 μm)

<Preparation of functional layer forming composition>
A composition for forming a functional layer (P-1) was prepared according to Preparation Example 1 below.

[Preparation example 1]
Disperse 1.00 g of cellulose nanocrystals ("NCV-100" manufactured by CelluForce, CNC in the table) in 99.00 g of ion-exchanged water and use "LUH300" manufactured by Yamato Scientific Co., Ltd. under the condition of 30% output for 3 minutes. An aqueous dispersion was obtained by performing ultrasonic treatment using a . To this aqueous dispersion, 33.00 g of silane-based quaternary ammonium salt (X-12-1139, 30 wt%, manufactured by Shin-Etsu Chemical Co., Ltd.) was added, and the mixture was stirred using a magnetic stirrer at 300 rpm for 2 hours at room temperature (25°C). The mixture was stirred using a . As described above, the unmodified nanocellulose was subjected to quaternary ammonium salt modification treatment to obtain quaternary ammonium salt modified nanocellulose (A-1).
Subsequently, as a binder resin, 96.7 g of light acrylate 9EG-A (trade name, manufactured by Kyoeisha Chemical Co., Ltd.) and 5.00 g of a polymerization initiator (Omnirad 2959, manufactured by IGM RESINS) were dissolved in 863.3 g of ion-exchanged water. After that, 40.00 g of quaternary ammonium salt-modified nanocellulose (A-1) was added to obtain a composition for forming a functional layer (P-1).

Nanocellulose (“NCV-100” manufactured by CelluForce) is a cellulose nanocrystal (CNC) with an average fiber diameter of 3 nm, an average fiber length of 76 nm, and an average aspect ratio (fiber length/fiber diameter) of 25.
Furthermore, even when unmodified nanocellulose is modified with quaternary ammonium salt, the average fiber diameter, average fiber length, and average aspect ratio (fiber length/fiber diameter) are expected to remain unchanged before and after modification with quaternary ammonium salt. .

<Preparation of adhesive layer forming composition>
A composition for forming an adhesive layer (P-2) was prepared according to Preparation Example 2 below.

[Preparation example 2]
1 kg of (meth)acrylic copolymer (x1), 50 g of crosslinking agent (x2), and 15 g of photopolymerization initiator (x3) were uniformly mixed to prepare a composition for forming an adhesive layer (P-2).

<Preparation of surface protection film>
[Example 1]
One side of the biaxially stretched polyester film was subjected to corona treatment to give a wettability index of 55 dynes or more to form a base layer. A primer layer coating solution containing 30% by mass of PEI was applied to the surface of the base layer using a bar coater, and heated at 100° C. for 1 minute to form a primer layer.
Subsequently, the functional layer composition (P-1) was applied to the surface of the primer layer using a bar coater, and after heat treatment was performed at 100° C. for 3 minutes, the main wavelength was 365 nm with an integrated light amount of 800 mJ/cm ² . A functional layer was formed by irradiating with ultraviolet rays, and a base material with a functional layer was obtained.
The aqueous coating liquids for the primer layer and the functional layer were mixed and used so as to have the solid content composition ratio and solid content thickness shown in Table 1.
Next, the adhesive layer forming composition was applied onto a release-treated polyethylene terephthalate film (Diafoil MRV, manufactured by Mitsubishi Chemical Corporation, thickness 100 μm) so that the thickness after drying was 25 μm. , heat treated at 100°C for 2 minutes. Thereafter, the base material surface of the functional layer-attached base material was bonded to the exposed surface of the adhesive layer to obtain a film laminate having the following structure: functional layer/primer layer/substrate/adhesive layer/release film.

[Example 2]
A film laminate was obtained in the same manner as in Example 1, except that the composition for forming a functional layer was configured as shown in Table 1.

[Example 3]
A film laminate was obtained in the same manner as in Example 1, except that the composition for forming a functional layer had the composition shown in Table 1, and heat treatment was performed at 160° C. for 30 minutes instead of ultraviolet irradiation.

[Comparative Example 1] to [Comparative Example 2]
A film laminate was obtained in the same manner as in Example 3, except that the composition for forming a functional layer was configured as shown in Table 1.

[Comparative example 3]
A film laminate was obtained in the same manner as in Example 1, except that the composition for forming a functional layer had the composition shown in Table 1.

Table 1 shows the materials and evaluation results of the film laminates of Examples 1 to 3 and Comparative Examples 1 to 3.
In addition, the base film with the functional layer before providing the adhesive layer was used for the measurement of total light transmittance, the measurement of haze, and the antibacterial property test.

From Examples 1 to 3, it was found that when the functional layer contained quaternary ammonium salt-modified cellulose nanocrystals, the surface protection film maintained its antibacterial properties even after UV irradiation.
On the other hand, it was found that Comparative Example 2, in which the functional layer did not contain quaternary ammonium salt-modified cellulose nanocrystals, did not have antibacterial performance even before UV irradiation.
Comparative Example 1 containing an Ag-based antibacterial agent had good antibacterial properties, but was found to be inferior in UV resistance and halogen resistance.
On the other hand, Example 1 had good UV resistance and halogen resistance, and was able to maintain antibacterial performance even after UV irradiation, indicating that it has the ability to replace Ag-based antibacterial agents. Ta.
Furthermore, from a comparison between Examples 1 and 2 and Comparative Example 3, it was found that it was possible to impart anti-glare properties in addition to antibacterial properties. This is considered to be because Examples 1 and 2 had suitable film haze and surface roughness (Sa) of the functional layer surface. Therefore, the surface protection film of the present invention can be applied to applications that require anti-glare properties, for example, and has the advantage that the range of application can be further expanded than before.

Claims (19)

(A) A surface protection film in which a functional layer containing ammonium salt-modified nanocellulose, a base layer, and an adhesive layer are laminated in this order. The surface protection film according to claim 1, wherein (A) ammonium salt-modified nanocellulose is (A') quaternary ammonium salt-modified nanocellulose. The surface protection film according to claim 1 or 2, wherein the functional layer further contains (B) a binder resin. The surface protection film according to claim 3, wherein the binder resin (B) is a water-soluble polymer. The surface protection film according to claim 4, wherein the water-soluble polymer is a polyvinyl alcohol resin or an acrylic resin. The surface protection film according to any one of claims 1 to 5, further comprising a primer layer between the functional layer and the base layer. The surface protection film according to claim 6, wherein the primer layer contains a polyvalent cation resin. The surface protection film according to claim 7, wherein the polyvalent cation resin is polyethyleneimine. The surface protection film according to any one of claims 1 to 8, wherein the functional layer has a thickness (after drying) of 10 nm or more and 1,000 nm or less. The surface protection film according to any one of claims 1 to 9, wherein the base material layer is a resin film, a fibrous base material, or glass. The surface protection film according to claim 10, wherein the resin film is a polyester film. The surface protection film according to any one of claims 1 to 11, wherein the adhesive layer is silicone-based, acrylic-based, or urethane-based. The surface protection film according to any one of claims 1 to 12, which has an antibacterial activity value of 3 or more against Staphylococcus aureus after being irradiated with ultraviolet light of 340 to 400 nm at 60 W/m ² for 10 hours. The surface protection film according to any one of claims 1 to 13, which has an antibacterial activity value of 3 or more for E. coli after being irradiated with ultraviolet light of 340 to 400 nm at 60 W/m ² for 10 hours. A film laminate comprising the surface protection film according to any one of claims 1 to 14 bonded to an adherend. The film laminate according to claim 15, wherein the adherend is a release film. The film laminate according to claim 15, wherein the adherend is glass. The surface protection film according to any one of claims 1 to 14, which is for a smart mirror. The film laminate according to claim 15 or 17, wherein the adherend is a smart mirror.